FIG. 17 is a perspective outline drawing of a folding hand-held electronic apparatus disclosed in Japanese Patent Application Non-Examined Publication No. H11-30226. A conventional coupling device shown in FIG. 17 comprises hinge mechanism 5 and swivel mechanism 6.
Hinge mechanism 5 connects first flat electronic apparatus 2 having display 1 to second flat electronic apparatus 4 having operating board 3 such that apparatus 2 and apparatus 4 can be folded.
Swivel mechanism 6 is disposed between first apparatus 2 and hinge mechanism 5 and allows a user to swivel first apparatus 2 arbitrarily. As shown in FIG. 18 and FIG. 19, the hand-held electronic apparatus can be folded in two ways, i.e., (1) display 1 of first apparatus 2 shows inside and faces closely to operating board 3 of apparatus 4, and (2) contrary to case (1), display 1 shows outside.
Swivel mechanism 6 includes cylinder 7 and cylinder 8 fitted to each other, and this fitting allows both of cylinders 7 and 8 to swivel, as shown in a sectional view of FIG. 20. First apparatus 2 is mounted to cylinder 7, and cylinder 8 is mounted to hinge mechanism 5. Spring 13 urges cylinder 7 against cylinder 8 in order to supply a predetermined frictional resistance to the swiveling of first apparatus 2.
FIG. 21A and FIG. 21B illustrate each end face, opposite to each other, of cylinder 7 and cylinder 8 respectively. Protrusion 9 and guide groove 10 regulate a swivelable range of first apparatus 2 from its front side to reverse side, i.e., turned over. Protrusion 12 and recess 14 hold first apparatus 2 at either end of the swivelable range by clicking apparatus 2 into place with pressure of spring 13.
However, in the hand-held electronic apparatus using the conventional coupling device discussed above, when first apparatus 2 and second apparatus 4 are in an open position as shown in FIG. 17, first apparatus 2 can be stopped at an intermediate place within the swivelable range. If a user carelessly folds the hand-held electronic apparatus when first apparatus 2 is held perpendicular to second apparatus 4, a corner of first apparatus 2 may damage second apparatus 4.